ISOTHERMAL FORGING OF TIAL-BASED INTERMETALLIC COMPOUNDS

Fundamental study of the high temperature deformation of titanium aluminide, TiAl, has been conducted in order to develop the manufacturing process using isothermal forging. The flow stress was exactly expressed using Zenner-Hollomon parameter as well as common metals. The recrystallization occurred during high temperature deformation, and structure was transformed from the lamellar structure to the fine recrystallized grain structure. And there were some deformation conditions where TiAl could be deformed without any defects up to 80% degree of reduction from as cast state. On the basis of above information, manufacturing of pancakes was carried out by isothermal forging. It was confirmed that it was possible to work plastically even from cast ingots samples and that mechanical properties could be improved by isothermal forging. These results suggest that the isothermal forging is a extremely effective process for manufacturing processes of TiAl.